Radar detection in multipath

An analysis of the detection of radar targets in multipath environments is presented. Radar targets often undergo enhancements or fades due to multipa th where the direct-path energy combines with a phase-shifted reflection to enhance or reduce the received energy. This phenomenon is a function of fr equency. Radars are often designed to avoid the problems of fades by changi ng frequency or using an assortment of frequencies in an M-out-of-N detecto r. To understand the detection statistics and choose M and M, the probabili ty density function (PDF) of the noise plus the tar-get times the multipath propagation factor must be known. This PDF is derived for a nonfluctuating target and for a Rayleigh target. The PDF is used to show the benefits of choosing the best M for a multipath environment compared to using the M tha t would be chosen in a free-space environment.